Understanding Soil Microbiology

The study of soil microbiology as it relates to forensic science is a relatively novel idea. While DNA, dental records, and trace evidence has been used to determine identities of both suspects and victims, along with location of crime scene and other details, soil could potentially be used to determine if a victim was placed in a location then removed. By studying the microbial composition of soils around a decomposing body, scientists will be able to track the fluctuations and changes of microbes from the soil. Using this data, it could be determined how old a dump site location is, or if someone reported a dump site, this data could support or disprove such claims.

First, it is important that scientists understand the basics of normal soil microbiology. Soil microbiology was once studied by sampling soil sites and simply counting microbes from the samples [1]. This was not sufficient enough to develop a better understanding of the microbial composition of the soil.  Since these methods were not efficient enough, soil enzymes were studied. Because the presence of enzymes in the soil is indicative of the presence of microbes, it is important to study the enzymes that are found. By studying these enzymes, and through the knowledge of microbiology, scientists are able to link the enzymes with certain bacteria that undergo various enzymatic activities in order to survive in the soil [1].

Enzyme testing is not without its faults, however. Simply using the enzymes found in the soil and a background of microbiology will not show, for certain, which microbes can be classified as being present in the soil [1]. Instead of using enzymatic testing as confirmatory and characterizing tests, scientists will use the data gathered from these methods to monitor various details of the soil. Various approaches to testing soil have been proposed over the years in efforts to more clearly classify the microbiota of soil. Through enzymatic testing and metabolic analysis, the compositions of soils are better understood than they were fifty years ago, but the complete classification is still out of grasp.

Even more recently developed, DNA sequencing of soil samples has proven to be a relatively well informative method for determining what, and just how many, microbes compose the soil. While there are several methods which are currently used to study the DNA or RNA of soil microbiology, several in the science community have supported the ideas that molecular ecology is essential for the study of soil microbiology [1]. The future of understanding the microbiology of soil is still geared towards the continued study of microbial composition and activities through the use of molecular techniques [1]. Due to the vast contrast between the many soil types, along with the added complexities from climate, altitude, and geographic location, the complete composition of soil microbiota may never be absolutely determined. Along with all these complicating factors, the changes that are constantly taking place in these factors will continue to keep the soil microbiology from being completely determined.

By knowing the basics of soil microbiology, scientists should one day be able to more widely apply what is known in order to utilize soil from forensic cases to determine a variety of evidentiary information. Through the knowledge of general soil characteristics, scientists can already begin to study forensic applications for this information in efforts to utilize another route of evidence to help solve crimes. Because we already see widespread changes in crime scenes from the more well known aspects of crime investigation due to television, perhaps developing new techniques to uncovering clues will prove to be beneficial not only to the scientific community, but the criminal justice community as well.

Resources:

1. Insam, H. (2001). Developments in soil microbiology since the mid 1960s. Geoderma, 100, 389-402.